The Steamboating Forum

Quick question, what's the best oil for running in a new engine?
Thanks
Ian

That's a slightly more complicated question than it appears.

Almost all steam launch engines use on on a "total loss" basis: i.e. it isn't recycled and filtered. Futhermore, peak temperatures and pressures in cylinders are usually lower than in internal combustion engines. Taken together that means that the oil type is less critical than for e.g. motor car engines, because if it degrades a bit on first pass, it gets discarded anyway.

If the engine is going to be operated with little or no superheat (i.e. near saturated steam) then many would say that cylinder oil is unnecessary, or even undesirable, and that condensed water plus graphite in grey cast iron pistons and cylinders will do the job. My personal preference is for a SMALL amount of steam oil (probably tallow containing) and the action for running in is simply to take it easy with rpm and throttle opening for the first few hours. Remember that large amounts of oil getting into a boiler can be very bad for it, if the system is condensing rather than puffing.

For the bearings and slides, the oil supply (whatever it is) can be increased a bit at first, but I doubt that will make a great deal of difference, and the more important action is to take it easy again, and thoroughly CHECK oil is getting to where it's needed. Some automatic oilers have a single supply for cylinder and valve oil, as well as the external bearings, and so you're forced to use a steam oil for the bearings, which is not ideal, but should be absolutely fine. Checking is clear enough for any system using an oil can, but for the more sophisticated systems with multiple fine tubes and/or internal oilways taking oil to the bearings etc. (which are generally better) checking is perhaps even more important until you're sure of the system. A tube with a bore of under 1mm is easily blocked by swarf or other debris, and even worse, perhaps intermittently blocked.

I suppose the other, and very effective, check when the engine is new, is to stop it regularly and feel all the bearings by hand: warm is fine, especially if all of them are much the same. One significantly hotter than the rest is bad news, and if you're sure it's getting enough oil, the next step would be to take it apart and ease it slightly, using metal polish or some other very fine abrasive (& then an VERY thorough clean before re-assembly).

Hello Ian,

what sort of oil you use for running in a new engine depends from the material of cylinder, piston, piston rings and bearings.

If piston and cylinder are made from cast iron then is a god cylinder oil like Z1000 recommended, for bearings you should use a god gear oil SAE80/90. To feel the temperature of the bearings by hand is god way to prevent from disaster.
To reduce the friction at the crosshead guidings you can also use a bit of molybdenum disulfide (MoS2).

Best Dietrich

For my power plant, 140 p.s.i. max and no superheat, I use no internal lubrication and chain saw bar oil for everything else.

Lopez Mike wrote:For my power plant, 140 p.s.i. max and no superheat, I use no internal lubrication and chain saw bar oil for everything else.

I had a chainsaw which was elderly, but worked well except for the oil pump drive, which was intermittent, and expensive to replace. Hence I have an oil can filled with bar oil, which gets used for all sorts of things as well as saw chains, and the really sticky texture is often handy. Steamboat bearings hadn't occurred to me as a use, but it could do very nicely: nice one Mike.

Hard to imagine a worse environment for a lubricant than a chainsaw bar. Wet, dirty and high speed. So far it's been working for me.